The present invention relates to a semiconductor chip and wiring board and method of manufacturing the same, semiconductor wafer, semiconductor device, circuit board, and electronic instrument.
Due to the advancement of high integration of semiconductor integrated circuits and size reduction of semiconductor chips, a mounting technique is required to cope with terminal connection at fine pitches. The mounting technique, readily coping with such requirement, includes TAB (Tape Automated Bonding) mounting being used for TCP (Tape Carrier Package) and flip-chip mounting being used for CSP (Chip Size Package).
In such mounting technique, bumps usually are provided on the pads of a semiconductor chip. The bump, typically an Au bump, is generally provided by an electrolytic plating method. Explained below is a method of forming an Au-bump electrode due to the electrolytic plating method.
FIG. 14 is a sectional view of an Au bump in the conventional semiconductor chip. A pad 12, as a part of wiring connected to an internal integrated circuit, is covered with a passivation film 14 in a portion except for an electrical connection surface thereof.
At first, an under-bump metal layer (lamination of barrier metal and adhesion metal layers) 1 is formed by a sputtering. Then, a resist layer 2, for forming a bump, is formed exposing an electrical connection portion of the pad 12 and it's surrounding by a photolithography technique. Next, Au is grown following a pattern of the resist layer 2 by an electrolytic plating method. After stripping the resist layer 2 away, the under-bump metal layer 1 is wet-etched depending upon a kind of the layer, through a mask of Au grown by plating. Thereafter, a bump 3 is formed through annealing and the like. Cleaning step is properly done in appropriate stages. In this manner, the bump-forming step by an electrolytic plating method takes a long time and hence requires further rationalization.
Therefore, there is a recent proposal to form a bump by an electroless plating method. In forming a bump by an electroless plating method, there is no need for a sputter and etching step for an under-bump metal layer. This can greatly reduce the step, thus realizing to form a bump at low cost. However, in the case of forming a bump by an electroless plating method, no under-bump metal layer is formed. Accordingly, there is a need to prevent water from entering to the pad.